fix(daemon): publish status files atomically - #949
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Included review availability: 0 reviews are currently available. Your included PR review attempts over the past 7 days set your current allowance at 4 reviews per hour. WalkthroughThe daemon now secures runtime directories and publishes status files through a bound ChangesDaemon file security and publication
Estimated code review effort: 4 (Complex) | ~45 minutes Merge Risk: 🔵 Low · up to The PR makes daemon status publication atomic and protects readers from incomplete documents, with broad verification covering replacement, cleanup, permissions, and platform behavior. A bounded permissions risk remains in handling pre-existing crash directories, so the change is mergeable with explicit owner awareness or follow-up. Sequence Diagram(s)sequenceDiagram
participant Server
participant StatusRoot
participant TemporaryStatusFile
participant LiveStatusFile
participant ParentDirectory
Server->>StatusRoot: Validate and bind status directory
Server->>TemporaryStatusFile: Create and write complete status document
Server->>TemporaryStatusFile: Sync and close temporary file
Server->>LiveStatusFile: Replace through bound root
Server->>ParentDirectory: Sync bound directory on supported platforms
Server-->>Server: Log committed-publication warnings
Suggested reviewers: 🚥 Pre-merge checks | ✅ 3 | ❌ 2❌ Failed checks (2 warnings)
✅ Passed checks (3 passed)
Full details: Linked Issues checkExplanation The changes satisfy issue Full details: Out of Scope Changes checkExplanation The PR includes changes beyond issue ✨ Finishing Touches 💡 1📝 Generate docstrings 💡
🧪 Generate unit tests (beta)
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Inline comments:
In `@internal/daemon/status_file.go`:
- Around line 42-53: Update status publication to bind the trusted status
directory at use time via a directory handle or rooted filesystem API, rather
than resolving path names independently. Apply this to temporary creation,
ReplaceWithRetry, cleanup, and syncStatusParent, validating containment,
ownership, and permissions before use. Ensure cleanup and replacement cannot
follow swapped ancestors or symlinks, and add a regression test that swaps the
directory during publication.
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internal/daemon/server.gointernal/daemon/status_file.gointernal/daemon/status_file_test.go
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Vasanthdev2004
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You flagged that native Windows execution was not available to you, so I ran this on Windows. Two things came back, one blocking and one that corrects the residual note in your description.
TestWriteStatusFileBindsDirectoryDuringAncestorSwap fails on Windows. Deterministically, on every run:
--- FAIL: TestWriteStatusFileBindsDirectoryDuringAncestorSwap
status_file_test.go:229: move bound status directory: rename ...\live ...\moved:
The process cannot access the file because it is being used by another process.
Nothing else in the package fails, under -race -count=2.
The production code is fine. The test encodes a POSIX property: that a directory can be renamed while someone holds an open handle to it. Windows refuses that. I let the hook tolerate a refused rename instead of failing the test, and the publication behaves exactly as intended:
rename of the bound directory: ... being used by another process
writeStatusFile: <nil>
parsed version = 5 (the freshly published document, at the original path)
So on Windows the bound handle does not merely make the swap detectable, it makes the swap impossible while publication is in flight, which is a stronger guarantee than the test is trying to assert. Only the setup needs to change: gate the rename step on the platform, or keep it untagged and assert the stronger outcome where the rename is refused. Worth keeping the test either way, because what it protects is real.
The residual is real, but it is not an absent path. Your description says the Windows helper "can briefly expose an absent path to an external reader, but it does not expose partially written content". The second half holds exactly. The first half is the wrong error. Over 2000 publications with a reader looping as fast as it can:
complete JSON = 185042
partial JSON = 0
absent path = 0
other errors = 3758
Zero partial reads, which is the property this PR exists to establish, and zero absent paths. The 3758 are all one thing:
open ...\daemon.status: The process cannot access the file because it is being used by another process
IsNotExist=false
IsPermission=false
A sharing violation, not ENOENT. That matters for whoever consumes this file, because both of the obvious classifications are false: a reader that retries on os.IsNotExist will not retry on this, and one that treats anything else as fatal will report a broken daemon roughly two percent of the time under load. Worth correcting in the description and worth a sentence somewhere a consumer will see, since the fix on the reading side is a bounded retry on a transient open failure rather than on a missing file.
The rest reads well. Publishing through a unique same-directory temporary, syncing before the replace, and treating post-replacement warnings as committed rather than tearing down startup are all the right calls, and binding to the directory handle is a real improvement over doing it by pathname. I especially like that you proved the primary regression fails when the old os.WriteFile is restored; that is the part that makes the rest of the coverage worth reading.
Fix the test and I will approve. Windows Smoke had not run when I looked, so this is ahead of CI rather than a report of it.
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Inline comments:
In `@internal/daemon/status_dir_owner_windows.go`:
- Around line 7-11: Update checkStatusDirOwner to fail closed on Windows unless
the status directory’s owner and DACL establish owner-only access; do not return
nil when ownership cannot be validated. Ensure status publication is rejected
for directories writable by other principals, and add a Windows regression test
covering an unsafe directory.
Apply the same fix in `@internal/daemon/status_dir_owner_unix.go` around lines 12
- 14: The Unix unsupported-metadata case is the same fail-open
ownership-validation issue.
In `@internal/daemon/status_file.go`:
- Around line 111-112: Update the error handling around RenameWithRetry in
Server.writeStatusFile to detect *fsutil.CommittedReplacementCleanupError, mark
status publication as committed, and return statusFileCommittedError; preserve
the existing wrapped-error path for all other failures.
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internal/daemon/server.gointernal/daemon/server_test.gointernal/daemon/status_dir_owner_unix.gointernal/daemon/status_dir_owner_windows.gointernal/daemon/status_file.gointernal/daemon/status_file_test.go
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@Vasanthdev2004 Fixed the Windows test assumption in cb128ec. The ancestor-swap regression now asserts the stronger Windows behavior: the open root handle blocks the directory rename, publication succeeds at the original path, the new document parses at the expected version, and no temp remains. On Unix it retains the moved-bound-directory/substitute-path assertions. I also corrected the PR note to describe transient Windows sharing violations rather than an absent path. Fresh Windows CI is running. |
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Windows CI on cb128ec exposed one additional platform fact: runner temp directories are owned by the access token default-owner SID, which may differ from the token user SID. Commit 018c94c now accepts either current-token SID, matching the repository existing Windows ownership invariant, while retaining handle-bound DACL validation. The focused daemon race suite passed 20 runs and the Windows test binary cross-compiled locally; fresh native Windows CI is running. |
jatmn
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jatmn
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I found issues that need to be addressed before this is ready.
Merge readiness
- [P1] Obtain a fresh approval for the Windows changes
internal/daemon/status_dir_owner_windows_test.go:20
GitHub currently reports this PR as blocked with an activeCHANGES_REQUESTEDdecision from Vasanthdev2004. The affected Windows test has changed and the old threads are resolved or outdated, but resolving threads does not clear that review decision. Please have the requested reviewer approve the current head, or have a maintainer dismiss the obsolete review, before merging.
Findings
-
[P1] Migrate Zero-created fallback directories before rejecting their mode
internal/daemon/status_file.go:140
This introduces an incompatible directory invariant for a path Zero already creates. WhenXDG_RUNTIME_DIRis unset,daemon.DefaultDirplacesdaemon.sock,daemon.lock, anddaemon.statusdirectly under~/.zero. The CLI's top-level panic handler usesobservability.DefaultCrashDir()(~/.zero/crashes), andWriteCrashReportcreates that hierarchy withMkdirAll(..., 0755). With the normal022umask, a crash occurring before the first daemon start therefore leaves~/.zeroat0755.Servelater callssecureSocketParent, but itsMkdirAll(..., 0700)is a no-op for an existing directory; this new check then rejects the directory before status publication withstatus directory permissions are 0755, want owner-only. The same current-user-owned state was accepted by the base implementation, so affected users lose daemon startup until they manually repair the mode.Please address the conflicting ownership/mode contracts at their shared root instead of merely relaxing this validation. Establish one private-runtime-directory invariant across every producer, safely migrate an existing directory only after proving through the bound handle that it belongs to the current user, and continue to fail closed if ownership or hardening cannot be established. If
~/.zeromust remain a general-purpose directory with broader compatibility requirements, put daemon runtime artifacts in a dedicated owner-only child and update every daemon path consumer consistently. Add an integration regression that starts with a fresh home, creates a crash report through the production helper, and then starts the daemon throughDefaultPaths; it should reach status publication without accepting a directory writable by another user.
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@jatmn @Vasanthdev2004 The requested runtime-directory compatibility fix is pushed in
Validation: focused regressions passed 50 runs, affected packages passed under |
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Windows CI on |
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minimal, and validate.
Inline comments:
In `@internal/observability/crash.go`:
- Line 29: Update the crash-directory setup around os.MkdirAll in the
crash-reporting flow to explicitly enforce owner-only permissions on the
existing directory chain, including pre-existing crash and parent directories,
before writing reports. Fail closed when any directory cannot be hardened, and
add coverage for pre-existing directories with broad permissions.
Apply the same fix in `@internal/observability/crash_test.go` around lines 32 -
56: The test-side coverage request is consolidated into the implementation
comment.
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📒 Files selected for processing (11)
internal/daemon/server.gointernal/daemon/server_test.gointernal/daemon/socket.gointernal/daemon/status_dir_owner_unix.gointernal/daemon/status_dir_owner_unix_test.gointernal/daemon/status_dir_owner_windows.gointernal/daemon/status_dir_owner_windows_test.gointernal/daemon/status_file.gointernal/daemon/status_file_test.gointernal/observability/crash.gointernal/observability/crash_test.go
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Windows CI on |
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@coderabbitai review Addressed the current-head crash-directory finding in
Focused migrations passed 50 runs, affected race tests pass, Windows binaries cross-compile, and build/smoke/vet/static analysis/govulncheck pass. Fresh native CI is running. |
🧩 Analysis chain🏁 Script executed: #!/bin/bash
set -euo pipefail
printf '%s\n' '== Current head and changed paths =='
git log -1 --format='%H%n%s'
git diff --name-status HEAD^ HEAD
printf '%s\n' '== Locate private-directory code and callers =='
fd -a -i 'privatedir|crash|socket|server' . | sort
rg -n -C 3 '\bEnsure\s*\(|\bsecureRuntimeDirectory\s*\(|\bWriteCrashReport\s*\(' \
-g '*.go' .
printf '%s\n' '== Compact source maps =='
for f in $(fd -a -e go . | rg '(^|/)(privatedir|crash|socket|server).*\.go$' || true); do
echo "--- $f"
ast-grep outline "$f" --items all --type function --view compact || true
doneLength of output: 11259 🏁 Script executed: #!/bin/bash
set -euo pipefail
printf '%s\n' '== Current-head patch =='
git diff --no-ext-diff --unified=80 HEAD^ HEAD -- \
internal/privatedir/privatedir.go \
internal/privatedir/privatedir_unix.go \
internal/privatedir/privatedir_windows.go \
internal/observability/crash.go \
internal/observability/crash_test.go \
internal/daemon/socket.go \
internal/daemon/status_file.go \
internal/daemon/status_dir_owner_unix.go \
internal/daemon/status_dir_owner_windows.go \
internal/daemon/status_file_test.go
printf '%s\n' '== New private-directory implementation with line numbers =='
for f in internal/privatedir/privatedir.go \
internal/privatedir/privatedir_unix.go \
internal/privatedir/privatedir_windows.go; do
echo "--- $f"
cat -n "$f"
done
printf '%s\n' '== Caller and test sections with line numbers =='
for spec in \
'internal/observability/crash.go:1:110' \
'internal/observability/crash_test.go:1:150' \
'internal/daemon/socket.go:1:120' \
'internal/daemon/status_file.go:1:260' \
'internal/daemon/status_dir_owner_unix.go:1:180' \
'internal/daemon/status_dir_owner_windows.go:1:300' \
'internal/daemon/status_file_test.go:320:430' \
'internal/daemon/server_test.go:120:210'; do
file=${spec%%:*}
rest=${spec#*:}
start=${rest%%:*}
end=${rest##*:}
echo "--- $file ($start-$end)"
sed -n "${start},${end}p" "$file" | nl -ba -v "$start"
doneLength of output: 48259 🏁 Script executed: #!/bin/bash
set -euo pipefail
printf '%s\n' '== Go version and private-directory test inventory =='
sed -n '1,80p' go.mod
rg -n -C 4 '\bprivatedir\.Ensure\s*\(|\bEnsure\s*\(' -g '*_test.go' -g '*.go' internal
printf '%s\n' '== Status publication flow =='
rg -n -C 8 'func \(.*\) writeStatusFile|func writeStatusFileAtomically|os\.OpenRoot|validateStatusRoot|privatedir\.Ensure' \
internal/daemon/status_file.go internal/daemon/server.go internal/daemon/socket.go
printf '%s\n' '== Paths defaults and daemon startup flow =='
rg -n -C 8 'type Paths|func DefaultPaths|DefaultPaths\s*\(|secureRuntimeParents\s*\(|func \(.*\) Serve|WriteCrashReport' \
-g '*.go' internal cmd
printf '%s\n' '== Relevant full source sections =='
for spec in \
'internal/daemon/status_file.go 1 180' \
'internal/daemon/server.go 1 180' \
'internal/daemon/socket.go 1 100' \
'internal/observability/crash_test.go 1 180' \
'internal/daemon/server_test.go 100 220'; do
set -- $spec
echo "--- $1 ($2-$3)"
sed -n "${2},${3}p" "$1"
done
printf '%s\n' '== Test files that mention private-directory behavior =='
rg -l -g '*_test.go' 'privatedir|broad.*directory|secure.*directory|owner-only' internal | sort | while read -r f; do
echo "--- $f"
rg -n -C 5 'privatedir|broad.*directory|secure.*directory|owner-only' "$f"
doneLength of output: 71632
I did not run builds or tests in the sandbox. The supplied verification image applies to an earlier commit. ✏️ Learnings added
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Vasanthdev2004
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Approving at d3c52384. Both of my findings are addressed, and I re-verified on Windows rather than reading the commits.
The test fix is the better of the two options I offered. You kept it untagged and asserted the stronger Windows outcome instead of skipping: version 6 published at the original path, no moved directory, no leftover temporaries. That is the right shape, because the behaviour it now pins is real and specific to the platform rather than merely absent there. internal/daemon passes natively here under -race -count=2.
The residual is described correctly now. "Windows readers can transiently receive a sharing violation ... they do not observe partial JSON or an absent path" matches what I measure exactly. Re-run on this head, since the six commits since touched the Windows path and I did not want to assume the property survived:
complete=173298 partial=0 absent=0 other=3884
first transient error: ... The process cannot access the file because it is being used by another process
Zero partial, zero absent, and the transient is the sharing violation, at roughly 2% under a reader spinning as fast as it can. The atomicity property holds.
On jatmn's first P1: that was my stale block, and this clears it. Worth saying plainly for the record rather than leaving it to be inferred.
On their second P1 I am not the right adjudicator, but it does not look stale-in-reverse. They reviewed 018c94cd, and two commits landed after: 34e93cf4 and d3c52384. Rather than relaxing the validation, those extract a shared internal/privatedir package with Unix and Windows implementations and route the crash-report producer through it, which is close to the "one private-runtime-directory invariant across every producer" they asked for. The want owner-only rejection is still there and still Unix-only, correctly skipped on Windows since DACLs are not mode bits. Whether that fully answers the existing-~/.zero-at-0755 case is theirs to judge; I am flagging that the commits address it structurally rather than by weakening the check.
One note, not a blocker. internal/privatedir is 218 lines across three files, including a 135-line Windows implementation, and has no test files of its own. I checked whether that means it is untested in practice and it does not: instrumenting Ensure shows it is reached during the Windows internal/daemon run, so the path has real indirect coverage. Still, for a package whose entire job is a security invariant, and which now has more than one consumer, direct tests would be worth having, particularly on the Windows side where the implementation is longest and the platform semantics least obvious.
gofmt clean, go vet clean for linux, darwin and windows, internal/privatedir, internal/observability and internal/daemon green, CI green.
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Summary
Root cause
writeStatusFileusedos.WriteFiledirectly ondaemon.status. That opens the existing live file with truncation before the replacement bytes are written, allowing a concurrent reader to observe empty or partial JSON and allowing an interrupted update to destroy the previous valid document.The first atomic-publication implementation still resolved temporary creation, replacement, cleanup, and parent sync from path strings independently. A directory or ancestor swapped between those steps could redirect a later operation. The follow-up binds every step to one validated
os.Rootdirectory handle.Regression coverage
Everyoneos.WriteFilecall is restoredPre-submission review
An evidence-first review traced the full
Serve -> writeStatusFile -> filesystem replacement -> cleanuplifecycle and inspected Unix and Windows behavior. It found and remediated the original post-commit error-classification defect. CodeRabbit then identified the remaining path-binding/TOCTOU gap; the follow-up commit binds all operations to one validated directory handle and adds a load-bearing directory-swap regression.Windows readers can transiently receive a sharing violation while the rooted replacement is in progress; they do not observe partial JSON or an absent path. Windows and Linux daemon tests were cross-compiled locally; native Windows runtime execution is covered by CI rather than the local macOS host.
Current-head verification
make fmt-checkgo vet ./...go test ./internal/daemon/...go test -race ./internal/daemon -count=20go run ./cmd/zero-release buildgo run ./cmd/zero-release smokemake lint-static— 0 issuesmake vulncheck— no vulnerabilities foundgit diff HEAD --checkThe current-head
go test ./...run reached and passed the daemon packages but encountered unrelated local user-config isolation failures ininternal/cli; the originally failing CLI doctor cases pass under an isolated home. Current-head CI passes the full Linux, macOS, and Windows workflows, including the native Windows test/build/smoke path.Initial terminal verification
Linked issue
Fixes #834
Checklist
issue-approvedlabel.gofmtclean.-race.Summary by CodeRabbit
Security Improvements
Reliability